Some patients experience phentermine withdrawal following the termination of their phentermine prescription. Symptoms of phentermine withdrawal can include fatigue, low mood (depression), trembling and insomnia among other reactions. Most people do NOT experience phentermine withdrawal , but those who do are understandably eager to know how long it lasts.
Acute phentermine withdrawal may last anywhere from about 1-4 days, but general stimulant withdrawal symptoms like depression and fatigue can linger for weeks or months after stopping the medication. As with all drugs, exact phentermine withdrawal time varies from person-to-person.
There exists little concrete evidence about phentermine withdrawal time given the fact that peer-reviewed studies show phentermine withdrawal does NOT occur, even in cases of extended use . However, actual phentermine users – especially those who have taken phentermine for long periods of time or at high doses – continue to report withdrawal symptoms with some frequency.
Phentermine withdrawal symptoms like depression, fatigue and trembling are typical of stimulant withdrawal. More, while phentermine is NOT an amphetamine, the two substances possess similar chemical structures, so some people draw parallels between the withdrawal symptoms from these two drugs.
Stimulant withdrawal symptoms can be broken-down into two main phases :
The initial crash takes place immediately after the last dose of the stimulant, while protracted withdrawal refers to the host of symptoms users experience in the days, weeks or months following their last binge.
In the first 12-36 hours after stopping a stimulant, the user experiences a “crash” that leaves him or her craving more. This rapid crash is responsible for the characteristic cravings/relapses associated with stimulant dependence.
Soon after, users may begin to experience psychological symptoms like increased anxiety, depression or inability to feel pleasure (anhedonia). This low feeling is often followed by intense fatigue, sometimes coupled with insomnia. At this point, it is common to fall asleep for an extended period of time, only to be awoken by intense hunger.
After this initial crash, symptoms of stimulant withdrawal tend to be the opposite of those experienced while taking the drug. In the 1-4 days after the last dose, users may feel:
Post-acute withdrawal symptoms (PAWS), such as depression/detachment, cravings and insomnia, may come and go over the next few weeks or months. Depression and feelings of unhappiness usually dissipate within 6-18 weeks after stopping the stimulant.
The biggest risk during stimulant withdrawal is the intense depression and inability to feel pleasure, which may be accompanied by suicidal ideation . Given the potential threat to self or others, it is absolutely critical that people going through stimulant withdrawal receive the support and treatment they need.
1. Hendricks, E. J., Srisurapanont, M., Schmidt, S. L., Haggard, M., Souter, S., Mitchell, C. L., ... Greenway F.L. (2014). Addiction potential of phentermine prescribed during long-term treatment of obesity. [Abstract]. International Journal of Obesity, 38(2), 292-298. doi:10.1038/ijo.2013.74
2. Center for Substance Abuse Treatment. (1999). Chapter 5 – Medical Aspects of Stimulant Use Disorders. In Treatment Improvement Protocol (TIP) (Ser. 33). Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK64323/